Combustion and heat transferring unit and method of manufacturing the same



May 15, 1934.

P. H. SEGNITZ COMBUSTION AND HEAT TRANSFERRING UNIT AND METHOD OFMANUFACTURING THE SAME Filed March 3, 1932 3nventor Patented May 15,1934 UNITED STATES PATENT OFFICE COMBUSTION AND HEAT TRANSFERRING UNITAND METHOD OF MANUFACTURING THE SAME poration of Delaware ApplicationMarch 3, 1932, Serial No. 596,424

18 Claims.

My invention relates to improvements in combustion and heat transferringunits and methods of manufacturing the same, with particular referenceto composition fuels intended for use in association with a holder whichnot only facilitates transportation and storage, but also facilitatesconcentration of heat of combustion for delivery to the article to beheat treated. Such units are peculiarly adapted for the vulcaniza tionof patches upon tire tubes and casings.

The primary object of my invention is to provide a fuel unit having acomposition fuel which is commercially marketable in briquette form inbonded association with a supporting member or container through which afactory predetermined number of heat units may be delivered at a factorypredetermined rate and for a factory predetermined period, intounvulcanized or partially vulcanized rubber or other material requiringsimilar heat treatment, and whereby vulcanizing operations and similarheat treatments may be performed without dependence upon the skill orexperience of the attendant or operator.

Various attempts have heretofore been made to produce a composition fuelhaving one or more grades of carbon as a base, but so far as I am awareno such fuel has heretofore been produced in which combustion, in asingle unit, can be initiated by simple ignition from the burning headof a match, and can be maintained in such single Lmit, andsatisfactorily regulated to produce uniform results. I have discoveredthat it is possible to produce a briquette having a carbon base whichwill be capable of an initial quick combustion until the temperaturereaches a predetermined degree and which will thereafter maintain suchtemperature for a desired period of time by a relatively slowcombustion, dependent for its maintenance upon the presence of materialwhich is comparatively inactive during the initial stages.

I have also discovered that such a briquette can be produced which willhave sufficient mechanical strength and capability of resistance to theinfluence of varying atmospheric conditions of heat and moisture toprevent disintegration or deterioration in combustible quality duringtransportation and storage, and which may be so molded in and bonded toa vulcanizing plate or pan as to produce a heating and heat transferringunit having all of the above mentioned desirable characteristics.

It is my object to utilize the above mentioned discoveries to produce anew article of manufacture for use with new and improved results inrepair vulcanization and in other arts having similar requirements forthe development of the desired temperature by quick combustion and themaintenance of such temperature by a subsequent slower rate ofcombustion during the de sired period of time.

More specifically, my objects are to produce a combustion and heattransferring unit which will include a bonded combustible briquettereadily ignited from the burning head of an ordinary match and capableof maintaining combustion without the aid of external heat derivedfromother units, or otherwise, and which will require no drafts or suppliesof oxygen from external sources in order to maintain combustion. Also toprovide such a unit which will not deteriorate either as to ease ofignition, rate of combustion, or in the bonding relation of thecombustible member to the heat transferring member by reason ofprolonged storage or variation in atmospheric conditions.

It is also my purpose to provide such a unit in which the porosity ofthe fuel can be accurately predetermined during the molding and bondingoperation and to provide such a unit with fuel of that type in which acarbon base is provided with oxygenating material adapted to maintainand also regulate combustion in accordance with the requirements fordelivery of a definite number of heat units through the heattransferring member, my invention contemplating the use of a compositionwhich is free from objectionable odor and capable of maintaining itsrelation to the heat transferring member during combustion, whereby theimproved unit may be peculiarly adapted for repair vulcanizationpurposes.

The work of vulcanizing patches upon tire tubes and casings isordinarily performed at the roadside by automobile drivers or bymechanics in garages. In either case the person who does the work isusually inexperienced, and uninformed as to the degree of heat requiredor the length of time during which a vulcanizing temperature should bemaintained. He is likely to be unacquainted with the fire hazardsinvolved or careless. Also, the prepared fuels heretofore employed forsuch purposes give oif objectionable fumes and are subject to widevariation in facility of ignition, rapidity of combustion, and thetendency of the fuel to remain in contact with the vulcanizing plateduring combustion, due to variations in moisture content. It has beencommon in commercial practice to employ fuels which readily absorbmoisture from the atmosphere in damp weather. jects is to avoid suchvariations.

It has long been known that compositions employing charcoal as a baseand having added thereto oxygenating substances adapted to maintaincombustion,,underneathian envelope of. ash, may be employed for heatingchafing dishes, foot warmers, and other articles requiring only a smallnumber of fuel briquettes at any given time, and the efforts of numerousexperimenters and inventors have been directed toward the preparation ofsuch composition fuels in-which the rate of combustion can besuccessfully regulated and maintained from which fuels, objectionablefumes or odors willmot be" given off during combustion. Various patentshave been granted for compositiqnsof thisgeneral character but so far asI am aware, none of them have been found to be sufficiently ,uniform inrate of combustion, temperature control andfreedom from objectionableodoras to make them serviceable for repair -vulcanizing operations, itwhich must be performed under widely variant atmospheric conditionsranging from openair conditionsto those existing in closed and poorlyventilated rooms. Examples of such fuels are to be found in the patentsto Berghausen et al.'-No.- 175,550 dated April 4, 1876,.and to=FrancisStoker No. 54 ,477, dated-May l, 1866. Modifications of such fuelsintended to fit them for use in vulcanizersare-suggested in the patenttow, Miles -No.-1,168;820 dated January 18,1916.

'It 'has also heretofore been customary. to: prepare a solution ofoxygenating material :andto impregnate a carbon base. therewith byimmersion --a-nd subsequent drying and-molding'into briquettes but -ithas not been found possible by such means to incorporate sufficientoxygenatingmaterial in a vulcanizing fuel, f for the .quantity requiredfor maintaining-combustion in a single thinbriquette such as is used inrepair vuloa-nizing exceeds a saturation limits. Also, the mixture ofcarbon with such solutions does not permit of the-necessary accuratepredetermination of the number of heat units to be evolved duringcombustion.

For these -reasons suchfuels, so far .as I am aware, =-have "not-heretofore been :regarded as commercially available for use inconnection with repair vulcanizers. Even :those operating undertheaforesaid patent towW.-H. Miles have preferred to employ animpregnated fibrous material suchas'is disclosed in patent of Jan. 8,1918 to -A.-B. Low No. 1,252,909, notwithstanding its-moisture absorbingand warping characteris tics and its tendency when dry, to burst intoflame.

Therefore, it is a specific object of my invention to overeome thedifficultiesheretofore encountered in the use, of composition fuels forpurposes of repairvulcanizationand to, develop a fuel have ingthe.following qualities or. characteristics:

.1. Uniform, unvaryin Droductionand delivery tothe. rubber patchingmaterial of. the required amount of heat, as closely, as possibleaccording to a previously defined heat curve.

-a. Complete. operation from ignition tofinal cooling, in approximately5 to 7 minutes.

b..Reaching.,and passing the 240 F. point as soon as possible afterignition.

c. Avoidance of a temperature in; excess of 300 F. at ,any. timein therubber patch.

d. Maintenance of a temperature in the patch One of my ohbetween 240 F.and 300 F. for about 3% min utes.

2. Dependable ease of ignition, with common match or wood safety match.

'3. Flameless combustion, with retention of high heat, or glow,.at leastunderneath the surface, during much of the vulcanizing period.

4. Freedom from an objectionable degree of smoke.

5. Freedom from objectionable odor.

6.: Freedom? from deterioration through absorption of atmosphericmoisture, or other effects of age or storage.

7.; Mechanical strength sufficient for ordinary handling, packing, andshipping requirements.

8.:Low cost, and commercial practicability of manufacture.

In the drawing:

"Figure l is a full sized isometric view of a combustion and heattransferring unit embodying my invention.

"Figure 2- is an enlarged sectional view of the same, drawn to line 22of Figure 1, showing the molding plunger inretracted position.

In the-manufacture of my improved fuel unit I employ-as a basea mixtureof two grades of substantially pure commercial carbon. One portion, orgrade, may be conveniently described as a slow burning carbon, hard intexture, of relatively coarse porosityandwith-a high ignitiontemperature. These characteristics arety-pified by ordinary gas coke,although any other form of carbon having similar qualities maybesubstituted with only minor changes in results.

This slow burning carbon should be ground to a relatively coarse powder,the particles of which will pass through a screen of preferably not lessthan 20 nor more than 50 mesh to the square inch. The other portion, orgrade,ofcarbon should be softer and finer in texture, with a relativelylow ignition point. Atypical example is hardwood charcoal, but evensofter carbon such as lamp black may be used. This grade of carbon maybe conveniently described as the quick burning carbon. It is ground to afine powder, preferably to a fineness which will enable it to passthrough a 60 mesh screen.

I- then mix the slow burning and quick burning carbon material insubstantially equal quantities by weight, adding to this mixture onehalf its total weight of dry powdered potassium chlorate andone quarterits weight of dry powdered sodium perborate. i

These four ingredients will then be thoroughly mixed with a suitablebinder and brought to a damp state by the addition of water, butpreferably the binder will be incorporated'by adding to the specifieddry ingredients a solution of water and a water-soluble gummy materialsuch for example as dextrin, gum arabic-or gum tragacanth. Theproportion of gummy material to. water will vary in accordance with thecharacteristics of the gum chosen and will range from approximately tenpercent of dextrin to about one percent for gum tragacanth.

The above named dry ingredients should first be thoroughly mixed, afterwhich a quantity of the aforesaid solution will be added and mixed withthe dry ingredients until the entire mass becomes sufliciently damp topermit of its compres- 31.

sion into briquettes under a comparatively light pressure, preferablynot exceeding pounds to the square inch. A quantity of the solution,equal in weight to about forty percent of the total Weight of the dryingredients, will carry into the j 1 mass approximately the correctproportions of water and of the binder to enable a briquette to beproducd in the manner now to be described.

After the mixture has been thus prepared and dampened it is placed upona thin metal vulcanizing plate, preferably of pan shaped formation, andsubjected to the aforesaid pressure in order to mold it into briquetteform and press it into adhesive intimate continuous contact with themetal surface, whereupon the pressure is removed and the plate utilizedas a holder which then becomes part of what may be convenientlydescribed as a bonded unit to be immediately transferred into an oven orto a drying rack where it is slowly dried under a moderate heat of about165 F. with minimum oxygen loss. If dried upon a rack in open air theoxygen loss will be proportionate to the temperature and humidity of theair, and the consequent time required for drying the materialsufficiently to make it readily ignitable from. the burning head of anordinary match. If the briquettes are dried in the open air at ordinaryroom temperatures the prolonged exposure to the atmosphere may beexpected to result in a considerable oxygen loss which will be indicatedby the blisters that will appear upon the surface of the briquette.

In Figure 1 I have illustrated a briquette 10 which has been molded asabove described by compressing it in a shallow circular pan. The panserves as a mold and when the pressure is applied, the briquette isbrought into pressure relation with the side wall 11 and also with thebottom 12 of the pan and during the drying operation a firm bond will beestablished between the pan and the combustible material. If desired,the side wall 11 of the pan may be formed with an inwardly projectingbead or lip 13 underneath which the briquette is formed in such a mannerthat the bead will assist in bonding the material to the pan under thebead and its margins cannot become separated and lifted by the gases ofcombustion when the briquette is ignited.

I also preferably provide the combustible material with a ventingaperture 14 extending from the bottom of the pan to its upper surface.This vent aperture may be conveniently formed during the compressingoperation by employing a compressing plunger 15 having a dependingtubular boss 16 which is equal in length to the depth of the completedbriquette and provided with a knife like lower edge to cut through thematerial, the latter being forced upwardly through the tubular boss tothe upper surface of the compressing plunger. In the formation ofsuccessive briquettes, the material within the boss will beprogressively forced outwardly at the top and therefore the briquettesmay be formed and perforated in a single operation.

Briquettes formed as herein described are made easily ignitable by thepresence of the quick burning carbon associated with the potassiumchlorate which readily yields up its oxygen at comparatively lowtemperatures, and due to the porosity of the briquette, the fire quicklypenetrates and between contiguous particles without expelling from themass any substantial quantity of the dampening and bonding solution.Such a pressure will substantially eliminate voids or pores in thedampened moisture but upon drying the desired degree of porosity will bedetermined by the quantity of water to be evaporated and such porositywill be found satisfactory.

By the time the briquette has been brought to the above describedtemperature by the quick burning material the relatively coarse grainsof slow burning carbon will have become ignited and will be suppliedwith oxygen by the perborate of sodium in sufficient quantity tomaintain a slow combustion of these harder grains of carbon at a ratesufiicient to maintain a vulcanizing temperature ranging from theinitial temperature of 240 F. to a maximum not materially exceeding 300F. in the rubber to which the bottom of the plate or pan is applied.Confinement to this range of temperature is possible by regulating theproportions of the ingredients used and also maintaining uniformconditions of use by preventing the briquette from warping or lifting.Three features may contribute to prevent warping or lifting, viz. theadhesive bond between the briquette and the contacting surface of thepan or plate, the retaining rib within which the surface of the marginof the briquette is in contact and the venting of the gases ofcombustion through the vent opening 14, thus preventing the developmentin the unit of any material internal pressure.

The bonding of these briquettes to the contacting surface of a pan orplate is usually accomplished by pressing the particles into intimateengagement with the metal surfaces, from which briquettes of thecharacter described do not withdraw or shrink during either the dryingprocess or during combustion. The terms bonding and bond are employed todistinguish my process and product from those in which materials areconnected with a holder by paste or glue, and also to distinguish fromcompositions which contain other materials which will burn, melt,volatilize, or shrink when drying in a manner to prevent the briquettefrom becoming permanently bonded, particle to particle and to contactingmetal surfaces, particularly ordinary unmachined surfaces which havesufficient irregularity of contour to provide anchorage. By providing anon-shrinking composition and molding it into the holder under pressureinstead of merely pouring it into the holder, I obtain a bond similar tothose obtained in the molding of brick material. Although the improvedbriquettes are composed of material which is largely combustible, thebond persists through the gas producing and disk warping stages ofcombustion.

When dried, the proportions of the various ingredients will besubstantially as follows.

I Parts by I weight Granular slow burning carbon material 2 Relativelyfine quick burning carbon materiaL 2 Potassium chlorate 2 Sodiumperborate 1 Binding material in quantity sumcient for briquetting andbonding purposes, the quantity being dependent upon the characteristicsof the binder employed.

The potassium chlorate will preferably be proportioned generally to theoxygen requirements of the quick burning carbon and the sodium perborateto therequirements of the slow burning carbon.

.For repair vulcanizing, a fuel charge of approximately four to four andone half grams, dry weight, is a sufficient quantity when bonded to athin sheet metal holder or pan, preferably formed from sheet metal ofstandard 23 B &'S gage or .023 inches in thickness, and one and threequarters of an inch in diameter. The fuel charge for sucha pan should beabout five thirty seconds (3%) of an inch in thickness when properlycompressed into a porous briquette in bonded relation to the pan. Such aunit is adapted for the vulcanization of tire and tube patches ofordinary size. But the size of the unit and the quantity of the fuelcharge is subject to wide variations in accordance with the weight andquantity of rubber to be vulcanized, and the heat storing anddistributing capacity of the holder which will of course vary inproportion to its thickness and conductivity.

By employing a pan having a thin bottom the heat units may be rapidlytransferred along lines substantially perpendicular to its surfacedirectly into the material, the pan serving as a pressure applyingmember. As combustion continues with diminishing rapidity in the lowerportion of the material after it has ceased in the visible portion it isthus possible to transfer heat units downwardly into the rubber insteadof allowing them to be dissipated in the surrounding atmosphere byemanation of flaming or heated gases. In the construction illustratedthe pan shaped holder is filled to the level of the. rib to the underside of which itis bonded. The portion above the rib facilitateshandling and applying theclamping' pressure through the holder to thematerial to be vulcanized.

It will be observed that in the fuel specifically described in theforegoing paragraph the quick burning material and the oxygenatingmaterial are of equal weight whereas the perborate of sodium is equal toone half of the weight of th slow burning carbon. While this is not tobe taken as indicating that the action of the two oxygenating materialsis separately directed to maintaining combustion in the respectivegrades of carbon, it does indicate a condition in which the desiredacceleration of initial combustion is accomplished, with a resultantprompt retardation in the rate of combustion between the time that thetemperaure reaches a desired minimum and the time when it mightotherwise exceed a desired maximum.

Some of the oxygen of the perborate of sodium is undoubtedly given upbefore the desired minimum of temperature is attained and some of thepotassium chlorate will continue to yield its oxygen after attainment ofthat temperature, and perhaps after the quick burning carbon has been sofar consumed that its heat of combustion is' no longer a material factorin temperature maintenance. The accumulation of ash resulting from thecombustion of this quick burning material will also act as a combustionretarding agent as well as a covering for the material in direct contactwith the heat transferring member, 1. e. the plate or pan. The ashresulting from this fuel is distinctly sintered and there is almostinvariably a sufficient fusion betweenparticles to keep the ash in asingle cinder-like unit. This is important for the reason that thecinder maintains an air excluding covering for the bottom of the pan.

I claim:

1. The'process of making combustion and heat transferring units,consisting in molding lnto briquette form, a mass of pulverulent fuel,an oxydizing agent and a bondingmaterlal into a metallic holder undersufficient pressure to establish a bonded relation between the fuel andthe holder adapted to maintain the bond between the fuel and the holderduring the warping and gas producing stages of combustion.

2. The process of making combustion and heat transferring units,consisting in molding into briquette form, a non-shrinking mass ofpulverulent fuel, an oxydizing agent and a bonding material into ametallic holder to establish a bonded relation between the fuel and theholder, having a melting and bond releasing co-efiicient above thetemperature developed by combustion during" the warping and gasproducing stages, and providing the molded mass with a vent having itslower. end closed to entry of atmospheric air.

3. The process of making combustion and heat transferring unitsconsisting in dry mixing granular slow burning carbon material,relatively fine quick burning carbon material, and oxygenating materialand then uniformly moistening the mixture and compressing it into fixedrelation to a heat conductive pressure applying member.

4. The process of making combustion and heat transferring unitsconsisting in dry mixing aquick burning carbon'base with substantiallyequal quantities, by weight, of a slow burning carbon base and potassiumchlorate, together with substantially a half portion of perborate ofsodium requiring approximately a vulcanizing temperature to slowlyrelease its oxygen, mixing the mass with a bonding material, dampeningit sufficiently to permit molding without expulsion of water and soluble.constituents, and molding it into briquette form under sufiicientpressure to produce a porous sinteringmass capable of 'maintainingcombustion independently of an exterior source of oxygen supply.

5. That step in the process of making combustion and heat transferringunits consisting in dry mixing two portions of slow burning and quickburning materials with an equal portion of oxygenating material,combustible largely with the quick burning material, and lesser.portions of more slowly acting oxygenating material responsive to avulcanizing temperature, and subsequently adding moisture and bondingmaterial to produce'a damp moldable mass.

6. As a new article of manufacture a sinterable briquette of lightporosity adapted for repair vulcanization and comprising a mixture of agranular carbon base, a relatively quick burningcarbon base and anoxygenating material capable of freely yielding oxygen to the quickburning carbon base during combustion and of a weight substantiallyequal to that of the quick burning carbon, a smaller portion ofrelatively slow acting. oxygenating material requiring substantially avulcanizing temperature for oxygen yield, and adapted for maintainingcombustion of the granular carbon in a single disk-like unit, and abinding material.

'7. A combustion and heat transferring unit comprising a solidified massof puverulent car bonaceous and self oxygenating materials and a holderin bonded relation thereto said mass of materials and the holder beingadapted to maintain said bonded relation during the warping and gasproducing stages of combustion.

8. As a new article of manufacture a combustion unit comprising thecombination of a granular slow burning carbon material, a relativelyfine quick burning carbon material, potassium chlorate in quantitysubstantially equal by weight to the Weight of the quick burning carbonmaterial, a half portion of perborate of sodium, and a bonding material,said unit being adapted, by its size, thickness and composition, totransfer a predetermined number of heat units through a metal platewithin a predetermined period of time required for vulcanizing repairpatches upon pneumatic tires.

9. A combustion and heat transferring unit comprising a non-shrinkingsolidified mass of pulverulent, carbonaceous and self oxygenatingmaterials, and a heat conductive non-combustible holder provided with aninwardly projecting bonding member adapted to marginally engage thecombustible material to hold it in contact with the bottom of theholder, said bottom of the holder being sufficiently thin to allowdownward heat transfer along substantially straight lines from the fuelto material against which the bottom of the holder rests said mass ofmaterial being adapted to uniformly maintain its relation to the holderduring combustion and to maintain combustion underneath the surfaceindependently of atmospheric conditions.

10. The combination with a vulcanizing clamping plate, of a sinteringbriquette thereon, individually capable of maintaining combustion for aperiod of time substantially predetermined by its compositionindependently of external influences, and means for holding thebriquette in contact relation to the plate during combustion throughoutits original contacting area, said briquette being capable of deliveringa substantially predetermined number of heat units through the plateduring combustion with sufiicient uniformity in rate of delivery toproperly vulcanize a repair patch.

11. A combustion and heat transferring unit comprising a solidified massof pulverulent, carbonaceous and self oxygenating materials, and a heatconductive non-combustible holder provided with an inwardly projectingbonding member adapted to marginally engage the combustible material tohold it in contact with the bottom of the holder, said fuel beingprovided with a vent aperture to release gases of combustion, and beingotherwise bonded to the bottom of the holder to prevent air draftsthrough said aperture during combustion.

12. A combustion and heat transferring unit comprising a poroussolidified mass composed of pulverulent quick burning carbonaceousmaterials, relatively slow burning carbonaceous mate rials, andoxygenating materials, said mass being composed of solid non-meltingparticles in porous bonded relation to each other and adapted forsintering during combustion, a heat conductive incombustible holderhaving a relatively thin bottom, and means for holding said material incontact with the bottom during transportation and also duringcombustion.

13. A combustion and heat transferring unit comprising the combinationwith a shallow heat transferring incombustible pan shaped holder, of anon-shrinking porous mass of pulverulent carbonaceous material mixedwith combustion maintaining material and a binding material in bondingrelation to the other materials and to the holder.

14. A combustion and heat transferring unit comprising the combinationwith a pan shaped holder having its sides provided with an inwardlyextending rib extending along a line substantially parallel with the panbottom, of a mass of compacted, porous, self oxygenating and sinterablecombustible material filling the holder space below said rib incontinuous compacted and bonded relation to the opposing surfaces of theholder and rib, and containing material for regulating the rate ofcombustion and predetermining its duration.

15. A combustion and heat transferring unit comprising the combinationwith a pan shaped holder having its sides provided with an inwardlyextending rib extending along a line substantially parallel with the panbottom, of a mass of sinterable combustible material filling the holderspace below said rib, and containing material for regulating the rate ofcombustion and predetermining its duration, said rib being adapted tomarginally hold said materials during combustion and aid in preventingaccess of external air to the upper surface of the bottom of the holder,said material being composed of particles adapted to remain in the solidstate during combustion and bonded in fixed relation to each other andin fixed heat transferring relation to the bottom of the holder, saidmaterials being capable of maintaining said heat transferring relationduring combustion.

16. A combustion and heat transferring unit comprising the combinationwith a holder having raised side walls, of a fuel briquette having apredetermined rate of combustion independently of atmospheric oxygen andother atmospheric conditions and means for maintaining the briquette inair excluding relation to the bottom and side Walls of the holder duringcombustion.

17. A combustion and heat transferring unit comprising a solidified massof non-melting pulverulent, carbonaceous and self oxygenating materialscapable of maintaining their relation to each other during combustionand adapted to leave a sintered residual heat retaining mass uponcompletion of combustion, and a heat conductive non-combustible holderin marginal engagement with the combustible material to hold it in contact with the bottom of the holder.

18. The process of making combustion and heat transferring units forvulcanizing purposes, consisting in molding a fuel briquette composed ofoxygenating materials and non-melting solid particles having differingrates of combustion and having predetermined combustion maintainingcharacteristics into a container adapted to serve as a clamping platefor applying pressure and transferring heat to the material to bevulcanized.

PAUL I-I. SEGNITZ.

